feat: 대시보드 API 및 FCM 푸시 알림 API 구현

Dashboard API:
- DashboardController, DashboardService 추가
- /dashboard/summary, /charts, /approvals 엔드포인트

Push Notification API:
- FCM 토큰 관리 (등록/해제/목록)
- 알림 설정 관리 (유형별 on/off, 알림음 설정)
- 알림 유형: deposit, withdrawal, order, approval, attendance, notice, system
- 알림음: default, deposit, withdrawal, order, approval, urgent
- PushDeviceToken, PushNotificationSetting 모델
- Swagger 문서 추가

app/Http/Requests/Push/UpdateSettingsRequest.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace App\Http\Requests\Push;
+
+use App\Models\PushNotificationSetting;
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Rule;
+
+class UpdateSettingsRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'settings' => ['required', 'array'],
+            'settings.*.notification_type' => [
+                'required',
+                'string',
+                Rule::in(PushNotificationSetting::getAllTypes()),
+            ],
+            'settings.*.is_enabled' => ['required', 'boolean'],
+            'settings.*.sound' => [
+                'nullable',
+                'string',
+                Rule::in(PushNotificationSetting::getAllSounds()),
+            ],
+            'settings.*.vibrate' => ['nullable', 'boolean'],
+            'settings.*.show_preview' => ['nullable', 'boolean'],
+        ];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'settings.required' => __('error.push.settings_required'),
+            'settings.*.notification_type.required' => __('error.push.type_required'),
+            'settings.*.notification_type.in' => __('error.push.type_invalid'),
+            'settings.*.is_enabled.required' => __('error.push.enabled_required'),
+        ];
+    }
+}